- Patients must not have any clinical evidence of congestive heart failure (CHF) (specifically, New York Heart Association [NYHA] class III [moderate] or class IV [severe]) at the time of registration; baseline echocardiogram within 28 days of registration must demonstrate an ejection fraction (EF) >= 50%; patients must have corrected QT (QTc) interval < 500 msec on prestudy electrocardiogram (EKG) and no known history of congenital long QT syndrome; patients must not have experienced unstable angina pectoris, clinically significant cardiac arrhythmias, or stroke (transient ischemic attack [TIA] or other ischemic event) within 3 months prior to registration and not have experienced myocardial infarction or thromboembolic event requiring anticoagulation within 6 months of registration; prestudy EKG must be obtained within 28 days prior to registration